Conventionally, if an image display device is connected to an image supplying device, the image supplying device is generally adapted to processing capability such as a compression method supported by the image display device. As the adapting method, a system and method for exchanging computer data processing capability between a computer related to the image display device and the like and a computer related to the image supplying device and the like is known (for example, see JP-A-7-203177). That is, it is possible to communicate information about the data processing capability between the computers.
In more detail, the computers exchange the capability such that data transmission between the computers can be performed with a most efficient data format with respect to the two computers. A first computer which receives a data file sends a data processing capability list to a second computer which transmits the data file to the first computer. The transmission computer checks the capability and determines the most efficient data format for transmission, similar to the capability list of the reception computer. The transmission computer can process the data file with an intermediate format, for efficient data transmission which allows the reception computer to process the intermediate data file with a desired data format.
Meanwhile, in an OSI communication method, in a case where plural pieces of data having different coding methods are transmitted, a technology of the OSI communication capable of improving the convenience of the communication in addition to simple communication control is known (for example, see JP-A-6-14083). In more detail, if a session connection is established, information about image data which will be transmitted, that is, CAPABILITY DATA SPDU including information about document image data and still image data, is transmitted. A called terminal includes its capability information, which can be communicated, in the CAPABILITY DATA ACK SPDU and responds thereto. A calling terminal receives the capability information, checks that a counterpart can be communicated, transmits ACTIVITY START SPDU, sequentially transmits the document image data and the still image data, and transmits ACTIVITY ENDS PDU.